It is well known to temporarily construct a scaffolding near and associated with a construction project that rises above the ground. The scaffold provides a means of holding construction materials and workers who apply the materials to the project.
Scaffolds are typically made of tubular materials that interconnect with hinge joints or other means. Vertical support members are arranged to act as columns and are fixedly connected to horizontal and tangential brace members to provide a structure of sufficient strength to carry the load of the scaffold, the load of the materials, and the load of the workers as the scaffold increases in height.
Typical scaffolding constructions utilize scaffold end frames having fixed horizontal support members that function as ladder rungs. Typically such horizontal support rungs do not extend the full width of the scaffold and this limits the width of the work surface that may be formed by placing work planks on the rungs.
Such fixed rungs are usually welded in place. Such an arrangement limits the number of working levels that may be formed by placing work planks on horizontal support members and between adjacent scaffold end frames.
It is an advantage to be able to establish a wide working surface at as many levels as necessary so that the work may be conveniently applied to the construction surface to which the scaffold is associated.
Others have sought to provide improvements to scaffolding as shown by the following U.S. Patents:
U.S. Pat. No. 2,476,863 to Hawes discloses merely a scaffolding clamp that may be used to join vertical and horizontal scaffold members. Similarly, U.S. Pat. No. 2,876,027 to Sulmonetti discloses a scaffold clamp instruction but of the swivel type.
U.S. Pat. No. 3,071,204 to Piltingsrud teaches a scaffold having adjustable vertical supports and adjustable diagonal bracing. U.S. Pat. No. 3,092,207 to Larder discloses a replaceable ladder rung but of a different construction.
U.S. Pat. No. 3,998,562 to Gostling teaches a scaffold support collar to be attached to a scaffold vertical support to receive horizontal support or rung members. U.S. Pat. No. 4,082,162 to Diez teaches a ladder extension construction having rungs which may be extended longitudinally to facilitate assembly but which are positioned at fixed levels.
Lastly, U.S. Pat. No. 4,111,579 to Knight teaches a scaffold clamp construction which does permit horizontal support members (rungs) to be positioned at different vertical levels relative to the scaffold vertical supports but does not provide the clamps integral with the horizontal rung.
To overcome the prior art shortcoming of failure to provide a scaffold with end frames having only fixed rungs with an added capability for supporting a work platform at additional levels, I have devised a novel scaffold construction with movable scaffold rungs.